A firestorm recently touched off across the 'net when a published article revealed a study that found up to 50 percent of the click-throughs on pay-per-click (PPC) engines were fraudulent. Even though the study pointed out that the majority of fraud occurs in highly competitive and upper-priced keywords, it was still a major clarion call for marketers who run any type of PPC campaign.

Fair Notice

Much like the industry of pay-per-click (PPC) itself, the technology to detect and prevent click-fraud is still in its infancy. While we've done our best to vet any companies or services we mention in this article, please remember that many of these companies are still quite new and their fraud-detection systems are still in their testing phases. Because we take pride in only recommending the highest quality products to our customers, we feel compelled to inform you that it's still too early to tell which companies will distinguish themselves within this specialty. We're conducting ongoing research in this area and will keep you posted. However, our mention of any company or service in this article does not imply a tacit endorsement of that company or service. Please exercise your own good judgment and use our research as a starting point.

The study was performed by web analytics provider ClickLab – a company that markets software designed to automatically track and diagnose click fraud. While the source may raise red flags suggesting a conflict of interest, numerous other independent studies have found that...